1. Field of the Invention
This invention concerns a photomultiplier that makes use of the photoelectric effect and a radiation detector that uses this photomultiplier.
2. Related Background of the Invention
As one type of photomultiplier, a so-called head-on photomultiplier is known. With this head-on photomultiplier, a sealed vacuum container is arranged by providing a light receiving plate at an end portion at one side of a cylindrical side tube and providing a stem at an end portion at the other side of the side tube, and a photoelectric surface is disposed on the inner surface of the light receiving plate. An arrangement is provided wherein an electron multiplier unit, with a plurality of stages of dynodes, and an anode are layered and positioned opposite the photoelectric surface, and a plurality of stem pins, respectively connected to the respective dynodes and the anode, are insertedly mounted in the stem so as to lead to the exterior from inside the sealed container. Incident light that is made incident through the light receiving plate is converted into electrons at the photoelectric surface, the electrons that are emitted from the photoelectric surface are successively multiplied at the electron multiplier unit, wherein predetermined voltages are applied via the respective stem pins to the respective diodes, and the electrons that reach the anode upon being multiplied are taken out as an electrical signal via an anode pin, which is one of the stem pins.
Among such photomultipliers, there is an arrangement, wherein the stem pins are respectively mounted insertedly in a metal stem via tapered hermetic glass and the anode and the electron multiplier unit are layered above the plurality of stem pins, and an arrangement, wherein the stem pins are directly mounted insertedly in a stem formed of a large, tapered hermetic glass and the anode and the electron multiplier unit are layered on this stem (see, for example, FIG. 1 and FIG. 7 of Japanese Published Unexamined Patent Application No. Hei. 5-290793).